Solar energy, a major renewable energy source, is increasingly being explored to produce hydrogen fuel via water splitting, to generate electricity in solar cells, and to remediate water of heavy metals and organic matter through the use of photocatalysts. Titania (TiO2) is perhaps the most extensively studied photocatalyst because it is abundant, inexpensive, stable in photochemical environments, and generates electron-hole pairs at energy levels appropriate to split water. Unfortunately, titania is a relatively poor photocatalyst because its large bandgap of 3.2 e V only allows absorption of ultraviolet (UV) light, which is only 5% of the total solar energy, and its fast electron-hole recombination rate leads to high losses. Titania typically requires cathodic cocatalysts such as platinum to reduce electron-hole recombination and to generate measurable photoactivity. Composites of titania and various carbon materials, such as carbon nanotubes (CNTs), graphene, and graphite have been explored to narrow titania's bandgap by carbon doping and to reduce photogenerated electron-hole recombination through efficient charge transfer from titania to carbon materials. However, the photocatalytic performance of such composites can be limited by low transparency or porosity of the substrate and surface area to volume ratio of the titania.